System and method for person or object position location utilizing impulse radio

ABSTRACT

A System and Method for Person or Object Position Location Utilizing Impulse Radio, comprising a plurality of reference impulse radios; an object or person to be tracked having a mobile impulse radio associated therewith; an architecture with an associated positioning algorithm associated with said plurality of impulse radio reference radios and said mobile impulse radio; and display means for displaying the position of the person or object whose position is to be determined.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of pending U.S. Nonprovisionalapplication Ser. No. 09/710,555 entitled “System and Method UsingImpulse Radio Technology to Track and Monitor Vehicles” filed Nov. 10,2000, which is a continuation-in-part of pending U.S. Nonprovisionalapplication Ser. No.09/407,106, entitled “System and Method forMonitoring Assets, Objects, People and Animals Utilizing Impulse Radio”filed Sep. 22, 1999 and of U.S. Pat. No. 6,300,903 Issued Oct. 9, 2001which is a continuation-in-part of U.S. Pat. No. 6,133,876, issued Oct.17, 2000 all of which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to positioning systemsand methods. More particularly, the present invention provides person orobject positioning in a predetermined area.

[0004] 2. Background of the Invention and Related Art

[0005] The ability to ascertain the location of an individual or objectoccurs in countless scenarios. One such scenario includes emergencysituations where an emergency worker is in a building wherein potentialdanger lies. An example of this is a firefighter fighting a fire insidea burning building. It would be very beneficial and potentially lifesaving to be able to track the movements and current location of afirefighter inside a burning building. Also, it would be veryadvantageous to be able to transmit information relating to the personwhose location is being tracked and surrounding environment whichsurrounds them. This would be an example of a scenario wherein thelocating area varies.

[0006] In the firefighter example, the location would vary depending onwhere the fire may be located. However, in numerous positioningembodiments the objects or persons whose position is to be determinedare located in a fixed area for at least a given period of time. In thisscenario the object or person may be moving within a given defined areaand its/their position is desired to be located. An example of this mayinclude tracking a prison guard inside of a prison. Danger is inherentin a prison environment and knowing where prison guards are within theconfines of a prison is vital. An additional benefit would be to notonly be able to know the location of a prison guard, but also to enablethe prison guard to communicate on the same device that is tracking hislocation. Furthermore, the ability to provide an emergency notificationwould be beneficial. Consequently, if one mobile unit could providecommunication, alerting and positioning, the benefits to prison guardswould be enormous.

[0007] Another example of a person or object moving within a definedarea is a child in a theme park such as Disney World in Orlando, Fla.This environment typically includes family members with children.Hundreds of children are lost in Disney World each year as childrenwander off if the parents turn their head for even a brief period. Thiscan be a very dangerous situation and there is an immense need to beable to find the lost child's exact position immediately. With thousandsof people and a large geographic area, this is a difficult task.

[0008] Another important task is to know the position of items in awarehouse. Billions of dollars are spent each year on shipping itemsfrom one location to another. Many times these items are stored inseveral locations prior to its arrival at the final destination. In aprior application, filed by the present inventor, application Ser. No.09/407,106, filed Sep. 27, 1999, entitled “System and Method forMonitoring Assets, Objects, People and Animals Utilizing Impulse Radio”,a method of tracking such items utilizing impulse radio was describedand is incorporated herein by reference. However, positioningarchitectures in that application were not used to determine the exactlocation of items within a warehouse or other area.

[0009] Further, numerous other techniques, both completely wireless andpartially non-wireless, have been attempted for position locating withlimited success. The reason for this limited success is the inherent RFproperties of existing technologies. In the burning building example,severe multipath problems exist as well as an extremely noisy RFenvironment is present. The RF environment is cluttered with emergencyradio signals from police and firemen as well as hand held radios fromfiremen working on the fire. Most buildings are filled with multipathpropagation problems and are inherently unreliable in that environment;and a fireman in a burning building is a situation that requires extremereliability.

[0010] In areas such as the Disney World example, attempts have beenmade to be able to locate people and objects, but again with limitedsuccess. The metal rides, the large buildings and many other multipathcausing things are present. Thus, a child may be in between two largebuildings and under a metal picnic table, cowering in fear for havinglost his parents, and conventional radios may not be able to find hisposition. Further, power and component requirements for conventionalwireless technology make placing transmitters with each childproblematic due to the size, expense and limited battery life of thetransmitters. Therefore, there is a strong need for a wireless positionlocating system that has advantageous multipath propagation properties,has low transmit power and can be mobile if needed. Also, there is aneed for a wireless locating system that, due to it's inherentproperties, can be implemented with a large number of varyingarchitectures.

SUMMARY OF THE INVENTION

[0011] It is therefore an object of the present invention to provide aposition locating system and method utilizing impulse radio techniques.

[0012] It is another object of the present invention to provide aposition locating system and method utilizing impulse radio that can bemobile or fixed.

[0013] It is a further object of the present invention to provide aposition locating system and method utilizing impulse radio with theability to implement a variety of positioning architectures depending onthe needs of the system and method.

[0014] These and other objects are provided, according to the presentinvention, by a plurality of impulse radio reference radios; an objector person to be tracked having a mobile impulse radio associatedtherewith; an architecture with an associated positioning algorithmassociated with said plurality of impulse radio reference radios andsaid mobile impulse radio; and display means for displaying the positionof the person or object whose position is to be determined.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present invention is described with reference to theaccompanying drawings. In the drawings, like reference numbers indicateidentical or functionally similar elements. Additionally, the left-mostdigit(s) of a reference number identifies the drawing in which thereference number first appears.

[0016]FIG. 1A illustrates a representative Gaussian Monocycle waveformin the time domain;

[0017]FIG. 1B illustrates the frequency domain amplitude of the GaussianMonocycle of FIG. 1A;

[0018]FIG. 2A illustrates a pulse train comprising pulses as in FIG. 1A;

[0019]FIG. 2B illustrates the frequency domain amplitude of the waveformof FIG. 2A;

[0020]FIG. 3 illustrates the frequency domain amplitude of a sequence oftime coded pulses;

[0021]FIG. 4 illustrates a typical received signal and interferencesignal;

[0022]FIG. 5A illustrates a typical geometrical configuration givingrise to multipath received signals;

[0023]FIG. 5B illustrates exemplary multipath signals in the timedomain;

[0024] FIGS. 5C-5E illustrate a signal plot of various multipathenvironments.

[0025]FIG. 5F illustrates the Rayleigh fading curve associated withnon-impulse radio transmissions in a multipath environment.

[0026]FIG. 5G illustrates a plurality of multipaths with a plurality ofreflectors from a transmitter to a receiver.

[0027]FIG. 5H graphically represents signal strength as volts vs. timein a direct path and multipath environment.

[0028]FIG. 6 illustrates a representative impulse radio transmitterfunctional diagram;

[0029]FIG. 7 illustrates a representative impulse radio receiverfunctional diagram;

[0030]FIG. 8A illustrates a representative received pulse signal at theinput to the correlator;

[0031]FIG. 8B illustrates a sequence of representative impulse signalsin the correlation process;

[0032]FIG. 9 illustrates the potential locus of results as a function ofthe various potential template time positions;

[0033]FIG. 9A illustrates four nodes in an Impulse Radio TDMA linkednetwork and the known distances between each node.

[0034]FIG. 9B illustrates the four time slots associated with a fournode Impulse Radio TDMA network.

[0035]FIG. 10 is an example of a full duplex positioning architecturewith synchronized transceiver tracking.

[0036]FIG. 11 is an example of a full duplex positioning architecturewith unsynchronized transceiver tracking.

[0037]FIG. 12 is an example of a transmitter positioning architecturewith synchronized transmitter tracking.

[0038]FIG. 13 is an example of a transmitter positioning architecturewith unsynchronized transmitter tracking.

[0039]FIG. 14 is an example of a receiver positioning architecture withsynchronized receiver tracking.

[0040]FIG. 15 is an example of a receiver positioning architecture withunsynchronized receiver tracking.

[0041]FIG. 16 is an example of a mixed mode positioning architecturewith mixed mode referenced radios.

[0042]FIG. 17 is an example of a mixed mode positioning architecturewith mixed mode mobile radios.

[0043]FIG. 18 is an example of a specialized antenna architecture withsteerable null antennae designs.

[0044]FIG. 19 is an example of a specialized antenna architecture withdifferent antennae designs.

[0045]FIG. 20 is an example of a specialized antenna architecture withdirectional antennae designs.

[0046]FIG. 21 is an example of amplitude tracking architectures withamplitude sensing tracking.

[0047]FIG. 22 is an example of navigation augmentation architectureswith GPS augmentation.

[0048]FIG. 23 is an example of navigation augmentation architectureswith GPS/INS augmentation.

[0049]FIG. 24 is an example of navigation augmentation architectureswith generic navigation sensor augmentation.

[0050]FIG. 25 illustrates impulse radio mobile positioning wherein theposition of firefighters within a building are determined.

[0051]FIG. 26 is a block diagram illustrating the components in theimpulse radio mobile positioning system and method of FIG. 25.

[0052]FIG. 27 illustrates the impulse radio fixed positioning systemwherein the location of a child in a theme park is depicted.

[0053]FIG. 28 is a flow chart of the process involved with the method oflocating the position of a lost child in a theme park that is equippedwith a system and method for position location using impulse radio.

[0054]FIG. 29 illustrates the impulse radio fixed positioning systemwherein the location of cargo in a warehouse is located.

[0055]FIG. 30 is a block diagram illustrating the components in theimpulse radio fixed positioning system and method as used in the cargoand warehouse example.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] Overview of the Invention

[0057] The present invention will now be described more fully in detailwith reference to the accompanying drawings, in which the preferredembodiments of the invention are shown. This invention should not,however, be construed as limited to the embodiments set forth herein;rather, they are provided so that this disclosure will be thorough andcomplete and will fully convey the scope of the invention to thoseskilled in art. Like numbers refer to like elements throughout.

[0058] Recent advances in communications technology have enabled anemerging, revolutionary ultra wideband technology (UWB) called impulseradio communications systems (hereinafter called impulse radio). Tobetter understand the benefits of impulse radio to the presentinvention, the following review of impulse radio follows. Impulse radiowas first fully described in a series of patents, including U.S. Pat.Nos. 4,641,317 (issued Feb. 3, 1987), 4,813,057 (issued Mar. 14, 1989),4,979,186 (issued Dec. 18, 1990) and 5,363,108 (issued Nov. 8, 1994) toLarry W. Fullerton. A second generation of impulse radio patents includeU.S. Pat. Nos. 5,677,927 (issued Oct. 14, 1997), 5,687,169 (issued Nov.11, 1997) and 5,832,035 (issued Nov. 3, 1998) to Fullerton et al. Thesepatent documents are incorporated herein by reference.

[0059] Uses of impulse radio systems are described in U.S. patentapplication Ser. No. 09/332,502 (Attorney Docket No. 1659.0720000),entitled, “System and Method for Intrusion Detection Using a Time DomainRadar Array,” and U.S. patent application Ser. No. 09/332,503 (AttorneyDocket No. 1659.0670000), entitled, “Wide Area Time Domain Radar Array,”both filed on Jun. 14, 1999 and both of which are assigned to theassignee of the present invention. These patent documents areincorporated herein by reference.

[0060] Impulse Radio Basics

[0061] This section is directed to technology basics and provides thereader with an introduction to impulse radio concepts, as well as otherrelevant aspects of communications theory. This section includessubsections relating to waveforms, pulse trains, coding for energysmoothing and channelization, modulation, reception and demodulation,interference resistance, processing gain, capacity, multipath andpropagation, distance measurement, and qualitative and quantitativecharacteristics of these concepts. It should be understood that thissection is provided to assist the reader with understanding the presentinvention, and should not be used to limit the scope of the presentinvention.

[0062] Impulse radio refers to a radio system based on short, low dutycycle pulses. An ideal impulse radio waveform is a short Gaussianmonocycle. As the name suggests, this waveform attempts to approach onecycle of radio frequency (RF) energy at a desired center frequency. Dueto implementation and other spectral limitations, this waveform may bealtered significantly in practice for a given application. Mostwaveforms with enough bandwidth approximate a Gaussian shape to a usefuldegree.

[0063] Impulse radio can use many types of modulation, including AM,time shift (also referred to as pulse position) and M-ary versions. Thetime shift method has simplicity and power output advantages that makeit desirable. In this document, the time shift method is used as anillustrative example.

[0064] In impulse radio communications, the pulse-to-pulse interval canbe varied on a pulse-by-pulse basis by two components: an informationcomponent and a pseudo-random code component. Generally, conventionalspread spectrum systems make use of pseudo-random codes to spread thenormally narrow band information signal over a relatively wide band offrequencies. A conventional spread spectrum receiver correlates thesesignals to retrieve the original information signal. Unlike conventionalspread spectrum systems, the pseudo-random code for impulse radiocommunications is not necessary for energy spreading because themonocycle pulses themselves have an inherently wide bandwidth. Instead,the pseudo-random code is used for channelization, energy smoothing inthe frequency domain, resistance to interference, and reducing theinterference potential to nearby receivers.

[0065] The impulse radio receiver is typically a direct conversionreceiver with a cross correlator front end in which the front endcoherently converts an electromagnetic pulse train of monocycle pulsesto a baseband signal in a single stage. The baseband signal is the basicinformation signal for the impulse radio communications system. It isoften found desirable to include a subcarrier with the baseband signalto help reduce the effects of amplifier drift and low frequency noise.The subcarrier that is typically implemented alternately reversesmodulation according to a known pattern at a rate faster than the datarate. This same pattern is used to reverse the process and restore theoriginal data pattern just before detection. This method permitsalternating current (AC) coupling of stages, or equivalent signalprocessing to eliminate direct current (DC) drift and errors from thedetection process. This method is described in detail in U.S. Pat. No.5,677,927 to Fullerton et al.

[0066] In impulse radio communications utilizing time shift modulation,each data bit typically time position modulates many pulses of theperiodic timing signal. This yields a modulated, coded timing signalthat comprises a train of identically shaped pulses for each single databit. The impulse radio receiver integrates multiple pulses to recoverthe transmitted information.

[0067] Waveforms

[0068] Impulse radio refers to a radio system based on short, low dutycycle pulses. In the widest bandwidth embodiment, the resulting waveformapproaches one cycle per pulse at the center frequency. In more narrowband embodiments, each pulse consists of a burst of cycles usually withsome spectral shaping to control the bandwidth to meet desiredproperties such as out of band emissions or in-band spectral flatness,or time domain peak power or burst off time attenuation.

[0069] For system analysis purposes, it is convenient to model thedesired waveform in an ideal sense to provide insight into the optimumbehavior for detail design guidance. One such waveform model that hasbeen useful is the Gaussian monocycle as shown in FIG. 1A. This waveformis representative of the transmitted pulse produced by a step functioninto an ultra-wideband antenna. The basic equation normalized to a peakvalue of 1 is as follows:${f_{mono}(t)} = {\sqrt{e}\left( \frac{t}{\sigma} \right)^{\frac{- t^{2}}{2\sigma^{2}}}}$

[0070] Where,

[0071] σ is a time scaling parameter,

[0072] t is time,

[0073] f_(mono)(t) is the waveform voltage, and

[0074] e is the natural logarithm base.

[0075] The frequency domain spectrum of the above waveform is shown inFIG. 1B. The corresponding equation is:${F_{mono}(f)} = {\left( {2\pi} \right)^{\frac{3}{2}}\sigma \quad f\quad ^{{- 2}{({\pi \quad \sigma \quad f})}^{2}}}$

[0076] The center frequency (f_(c)) or frequency of peak spectraldensity is: $f_{c} = \frac{1}{2\quad \pi \quad \sigma}$

[0077] These pulses, or bursts of cycles, may be produced by methodsdescribed in the patents referenced above or by other methods that areknown to one of ordinary skill in the art. Any practical implementationwill deviate from the ideal mathematical model by some amount. In fact,this deviation from ideal may be substantial and yet yield a system withacceptable performance. This is especially true for microwaveimplementations, where precise waveform shaping is difficult to achieve.These mathematical models are provided as an aid to describing idealoperation and are not intended to limit the invention. In fact, anyburst of cycles that adequately fills a given bandwidth and has anadequate on-off attenuation ratio for a given application will serve thepurpose of this invention.

[0078] A Pulse Train

[0079] Impulse radio systems can deliver one or more data bits perpulse; however, impulse radio systems more typically use pulse trains,not single pulses, for each data bit. As described in detail in thefollowing example system, the impulse radio transmitter produces andoutputs a train of pulses for each bit of information.

[0080] Prototypes built by the inventors have pulse repetitionfrequencies including 0.7 and 10 megapulses per second (Mpps, where eachmegapulse is 10⁶ pulses). FIGS. 2A and 2B are illustrations of theoutput of a typical 10 Mpps system with uncoded, unmodulated, 0.5nanosecond (ns) pulses 102. FIG. 2A shows a time domain representationof this sequence of pulses 102. FIG. 2B, which shows 60 MHZ at thecenter of the spectrum for the waveform of FIG. 2A, illustrates that theresult of the pulse train in the frequency domain is to produce aspectrum comprising a set of lines 204 spaced at the frequency of the 10Mpps pulse repetition rate. When the full spectrum is shown, theenvelope of the line spectrum follows the curve of the single pulsespectrum 104 of FIG. 1B. For this simple uncoded case, the power of thepulse train is spread among roughly two hundred comb lines. Each combline thus has a small fraction of the total power and presents much lessof an interference problem to receiver sharing the band.

[0081] It can also be observed from FIG. 2A that impulse radio systemstypically have very low average duty cycles resulting in average powersignificantly lower than peak power. The duty cycle of the signal in thepresent example is 0.5%, based on a 0.5 ns pulse in a 100 ns interval.

[0082] Coding for Energy Smoothing and Channelization

[0083] For high pulse rate systems, it may be necessary to more finelyspread the spectrum than is achieved by producing comb lines. This maybe done by pseudo-randomly positioning each pulse relative to itsnominal position.

[0084]FIG. 3 is a plot illustrating the impact of a pseudo-noise (PN)code dither on energy distribution in the frequency domain (Apseudo-noise, or PN code is a set of time positions defining thepseudo-random positioning for each pulse in a sequence of pulses). FIG.3, when compared to FIG. 2B, shows that the impact of using a PN code isto destroy the comb line structure and spread the energy more uniformly.This structure typically has slight variations which are characteristicof the specific code used.

[0085] The PN code also provides a method of establishing independentcommunication channels using impulse radio. PN codes can be designed tohave low cross correlation such that a pulse train using one code willseldom collide on more than one or two pulse positions with a pulsestrain using another code during any one data bit time. Since a data bitmay comprise hundreds of pulses, this represents a substantialattenuation of the unwanted channel.

[0086] Modulation

[0087] Any aspect of the waveform can be modulated to conveyinformation. Amplitude modulation, phase modulation, frequencymodulation, time shift modulation and M-ary versions of these have beenproposed. Both analog and digital forms have been implemented. Of these,digital time shift modulation has been demonstrated to have variousadvantages and can be easily implemented using a correlation receiverarchitecture.

[0088] Digital time shift modulation can be implemented by shifting thecoded time position by an additional amount (that is, in addition to PNcode dither) in response to the information signal. This amount istypically very small relative to the PN code shift. In a 10 Mpps systemwith a center frequency of 2 GHz., for example, the PN code may commandpulse position variations over a range of 100 ns; whereas, theinformation modulation may only deviate the pulse position by 150 ps.

[0089] Thus, in a pulse train of n pulses, each pulse is delayed adifferent amount from its respective time base clock position by anindividual code delay amount plus a modulation amount, where n is thenumber of pulses associated with a given data symbol digital bit.

[0090] Modulation further smooths the spectrum, minimizing structure inthe resulting spectrum.

[0091] Reception and Demodulation

[0092] Clearly, if there were a large number of impulse radio userswithin a confined area, there might be mutual interference. Further,while the PN coding minimizes that interference, as the number of usersrises, the probability of an individual pulse from one user's sequencebeing received simultaneously with a pulse from another user's sequenceincreases. Impulse radios are able to perform in these environments, inpart, because they do not depend on receiving every pulse. The impulseradio receiver performs a correlating, synchronous receiving function(at the RF level) that uses a statistical sampling and combining of manypulses to recover the transmitted information.

[0093] Impulse radio receivers typically integrate from 1 to 1000 ormore pulses to yield the demodulated output. The optimal number ofpulses over which the receiver integrates is dependent on a number ofvariables, including pulse rate, bit rate, interference levels, andrange.

[0094] Interference Resistance

[0095] Besides channelization and energy smoothing, the PN coding alsomakes impulse radios highly resistant to interference from all radiocommunications systems, including other impulse radio transmitters. Thisis critical as any other signals within the band occupied by an impulsesignal potentially interfere with the impulse radio. Since there arecurrently no unallocated bands available for impulse systems, they mustshare spectrum with other conventional radio systems without beingadversely affected. The PN code helps impulse systems discriminatebetween the intended impulse transmission and interfering transmissionsfrom others.

[0096]FIG. 4 illustrates the result of a narrow band sinusoidalinterference signal 402 overlaying an impulse radio signal 404. At theimpulse radio receiver, the input to the cross correlation would includethe narrow band signal 402, as well as the received ultrawide-bandimpulse radio signal 404. The input is sampled by the cross correlatorwith a PN dithered template signal 406. Without PN coding, the crosscorrelation would sample the interfering signal 402 with such regularitythat the interfering signals could cause significant interference to theimpulse radio receiver. However, when the transmitted impulse signal isencoded with the PN code dither (and the impulse radio receiver templatesignal 406 is synchronized with that identical PN code dither) thecorrelation samples the interfering signals pseudo-randomly. The samplesfrom the interfering signal add incoherently, increasing roughlyaccording to square root of the number of samples integrated; whereas,the impulse radio samples add coherently, increasing directly accordingto the number of samples integrated. Thus, integrating over many pulsesovercomes the impact of interference.

[0097] Processing Gain

[0098] Impulse radio is resistant to interference because of its largeprocessing gain. For typical spread spectrum systems, the definition ofprocessing gain, which quantifies the decrease in channel interferencewhen wide-band communications are used, is the ratio of the bandwidth ofthe channel to the bit rate of the information signal. For example, adirect sequence spread spectrum system with a 10 kHz informationbandwidth and a 10 MHZ channel bandwidth yields a processing gain of1000 or 30 dB. However, far greater processing gains are achieved withimpulse radio systems, where for the same 10 KHz information bandwidthis spread across a much greater 2 GHz. channel bandwidth, thetheoretical processing gain is 200,000 or 53 dB.

[0099] Capacity

[0100] It has been shown theoretically, using signal to noise arguments,that thousands of simultaneous voice channels are available to animpulse radio system as a result of the exceptional processing gain,which is due to the exceptionally wide spreading bandwidth.

[0101] For a simplistic user distribution, with N interfering users ofequal power equidistant from the receiver, the total interference signalto noise ratio as a result of these other users can be described by thefollowing equation: $V_{tot}^{2} = \frac{N\quad \sigma^{2}}{\sqrt{Z}}$

[0102] Where V² _(tot) is the total interference signal to noise ratiovariance, at the receiver;

[0103] N is the number of interfering users;

[0104] σ² is the signal to noise ratio variance resulting from one ofthe interfering signals with a single pulse cross correlation; and

[0105] Z is the number of pulses over which the receiver integrates torecover the modulation.

[0106] This relationship suggests that link quality degrades graduallyas the number of simultaneous users increases. It also shows theadvantage of integration gain. The number of users that can be supportedat the same interference level increases by the square root of thenumber of pulses integrated.

[0107] Multipath and Propagation

[0108] One of the striking advantages of impulse radio is its resistanceto multipath fading effects. Conventional narrow band systems aresubject to multipath through the Rayleigh fading process, where thesignals from many delayed reflections combine at the receiver antennaaccording to their seemingly random relative phases. This results inpossible summation or possible cancellation, depending on the specificpropagation to a given location. This situation occurs where the directpath signal is weak relative to the multipath signals, which representsa major portion of the potential coverage of a radio system. In mobilesystems, this results in wild signal strength fluctuations as a functionof distance traveled, where the changing mix of multipath signalsresults in signal strength fluctuations for every few feet of travel.

[0109] Impulse radios, however, can be substantially resistant to theseeffects. Impulses arriving from delayed multipath reflections typicallyarrive outside of the correlation time and thus can be ignored. Thisprocess is described in detail with reference to FIGS. 5A and 5B. InFIG. 5A, three propagation paths are shown. The direct path representingthe straight line distance between the transmitter and receiver is theshortest. Path 1 represents a grazing multipath reflection, which isvery close to the direct path. Path 2 represents a distant multipathreflection. Also shown are elliptical (or, in space, ellipsoidal) tracesthat represent other possible locations for reflections with the sametime delay.

[0110]FIG. 5B represents a time domain plot of the received waveformfrom this multipath propagation configuration. This figure comprisesthree doublet pulses as shown in FIG. 1A. The direct path signal is thereference signal and represents the shortest propagation time. The path1 signal is delayed slightly and actually overlaps and enhances thesignal strength at this delay value. Note that the reflected waves arereversed in polarity. The path 2 signal is delayed sufficiently that thewaveform is completely separated from the direct path signal. If thecorrelator template signal is positioned at the direct path signal, thepath 2 signal will produce no response. It can be seen that only themultipath signals resulting from very close reflectors have any effecton the reception of the direct path signal. The multipath signalsdelayed less than one quarter wave (one quarter wave is about 1.5inches, or 3.5 cm at 2 GHz center frequency) are the only multipathsignals that can attenuate the direct path signal. This region isequivalent to the first Fresnel zone familiar to narrow band sysetmsdesigners. Impulse radio, however, has no further nulls in the higherFresnel zones. The ability to avoid the highly variable attenuation frommultipath gives impulse radio significant performance advantages.

[0111]FIG. 5A illustrates a typical multipath situation, such as in abuilding, where there are many reflectors 5A04, 5A05 and multiplepropagation paths 5A02, 5A01. In this figure, a transmitter TX 5A06transmits a signal which propagates along the multiple propagation paths5A02, 5A04 to receiver RX 5A08, where the multiple reflected signals arecombined at the antenna.

[0112]FIG. 5B illustrates a resulting typical received composite pulsewaveform resulting from the multiple reflections and multiplepropagation paths 5A01, 5A02. In this figure, the direct path signal5A01 is shown as the first pulse signal received. The multiple reflectedsignals (“multipath signals”, or “multipath”) comprise the remainingresponse as illustrated.

[0113]FIGS. 5C, 5D, and 5E represent the received signal from a TM-UWBtransmitter in three different multipath environments. These figures arenot actual signal plots, but are hand drawn plots approximating typicalsignal plots. FIG. 5C illustrates the received signal in a very lowmultipath environment. This may occur in a building where the receiverantenna is in the middle of a room and is one meter from thetransmitter. This may also represent signals received from somedistance, such as 100 meters, in an open field where there are noobjects to produce reflections. In this situation, the predominant pulseis the first received pulse and the multipath reflections are too weakto be significant. FIG. 5D illustrates an intermediate multipathenvironment. This approximates the response from one room to the next ina building. The amplitude of the direct path signal is less than in FIG.5C and several reflected signals are of significant amplitude. (Notethat the scale has been increased to normalize the plot.) FIG. 5Eapproximates the response in a severe multipath environment such as:propagation through many rooms; from corner to corner in a building;within a metal cargo hold of a ship; within a metal truck trailer; orwithin an intermodal shipping container. In this scenario, the main pathsignal is weaker than in FIG. 5D. (Note that the scale has beenincreased again to normalize the plot.) In this situation, the directpath signal power is small relative to the total signal power from thereflections.

[0114] An impulse radio receiver in accordance with the presentinvention can receive the signal and demodulate the information usingeither the direct path signal or any multipath signal peak havingsufficient signal to noise ratio. Thus, the impulse radio receiver canselect the strongest response from among the many arriving signals. Inorder for the signals to cancel and produce a null at a given location,dozens of reflections would have to be cancelled simultaneously andprecisely while blocking the direct path—a highly unlikely scenario.This time separation of mulitipath signals together with time resolutionand selection by the receiver permit a type of time diversity thatvirtually eliminates cancellation of the signal. In a multiplecorrelator rake receiver, performance is further improved by collectingthe signal power from multiple signal peaks for additional signal tonoise performance.

[0115] Where the system of FIG. 5A is a narrow band system and thedelays are small relative to the data bit time, the received signal is asum of a large number of sine waves of random amplitude and phase. Inthe idealized limit, the resulting envelope amplitude has been shown tofollow a Rayleigh probability distribution as follows:${p(r)} = {\frac{1}{\sigma^{2}}{\exp \left( \frac{- r^{2}}{2\quad \sigma^{2}} \right)}}$

[0116] where r is the envelope amplitude of the combined multipathsignals, and 2σ² is the RMS power of the combined mulitpath signals.

[0117] This distribution shown in FIG. 5F. It can be seen in FIG. 5Fthat 10% of the time, the signal is more than 16 dB attenuated. Thissuggests that 16 dB fade margin is needed to provide 90% linkavailability. Values of fade margin from 10 to 40 dB have been suggestedfor various narrow band systems, depending on the required reliability.This characteristic has been the subject of much research and can bepartially improved by such techniques as antenna and frequencydiversity, but these techniques result in additional complexity andcost.

[0118] In a high multipath environment such as inside homes, offices,warehouses, automobiles, trailers, shipping containers, or outside inthe urban canyon or other situations where the propagation is such thatthe received signal is primarily scattered energy, impulse radio,according to the present invention, can avoid the Rayleigh fadingmechanism that limits performance of narrow band systems. This isillustrated in FIGS. 5G and 5H in a transmit and receive system in ahigh multipath environment 5G00, wherein the transmitter 5G06 transmitsto receiver 5G08 with the signals reflecting off reflectors 5G03 whichform multipaths 5G02. The direct path is illustrated as 5G01 with thesignal graphically illustrated at 5H02, with the vertical axis being thesignal strength in volts and horizontal axis representing time innanoseconds. Multipath signals are graphically illustrated at 5H04.

[0119] Distance Measurement

[0120] Important for positioning, impulse systems can measure distancesto extremely fine resolution because of the absence of ambiguous cyclesin the waveform. Narrow band systems, on the other hand, are limited tothe modulation envelope and cannot easily distinguish precisely which RFcycle is associated with each data bit because the cycle-to-cycleamplitude differences are so small they are masked by link or systemnoise. Since the impulse radio waveform has no multi-cycle ambiguity,this allows positive determination of the waveform position to less thana wavelength—potentially, down to the noise floor of the system. Thistime position measurement can be used to measure propagation delay todetermine link distance, and once link distance is known, to transfer atime reference to an equivalently high degree of precision. Theinventors of the present invention have built systems that have shownthe potential for centimeter distance resolution, which is equivalent toabout 30 ps of time transfer resolution. See, for example, commonlyowned, co-pending application Ser. Nos. 09/045,929, filed Mar. 23, 1998,titled “Ultrawide-Band Position Determination System and Method”, and09/083,993, filed May 26, 1998, titled “System and Method for DistanceMeasurement by Inphase and Quadrature Signals in a Radio System”, bothof which are incorporated herein by reference.

[0121] In addition to the methods articulated above, impulse radiotechnology along with Time Division Multiple Access algorithms and TimeDomain packet radios can achieve geo-positioning capabilities in a radionetwork. This geo-positioning method allows ranging to occur within anetwork of radios without the necessity of a full duplex exchange amongevery pair of radios.

[0122]FIG. 9A illustrates an example of a four slot TDMA network 90A. Webegin with all radios off the air. As the first radio, 92A, comes on, itpauses to listen to the current network traffic. After a reasonabledelay, it powers on and, having heard no other traffic, takes control ofthe first slot shown in FIG. 9B as 92B. While online, it willperiodically send a hello request containing identifying informationshowing it owns slot 1. Although the network is considered adhoc, theradio that owns the first TDMA slot has some unique responsibilities.

[0123] Radio B, 94A, powers up next and begins to listen to networktraffic. It notes that Radio A, 92A, is on the air in the first slot.Radio B, 94A, acquires slot 2, 94B, and transmits a hello request at theslot two position 2, 94B. The hello request prompts an exchange withRadio A, 92A, as soon as his slot comes available. Radio A transmits apacket that will result in the acquisition of two pieces of information.Radio A, 92A, sends a SYNC packet containing a request for an immediateacknowledgement. Radio B, 94A, is thereby given permission to respondduring Radio A's slot time. Radio B, 94A, transmits a SYNC ACK packet inreturn. Radio A, 92A, then calculates the distance to Radio B, 94A, andproperly adjusts the synchronization clock for the distance and sendsthe current time, adjusted for distance, to Radio B, 94A. At this pointRadio A's, 92A, clock is synchronized with Radio B, 94A. Once thisoccurs, any time Radio A, 92A, transmits, Radio B, 94A, is capable ofcalculating the distance to Radio A, 92A, without a full duplexexchange. Also any time Radio B, 94A, transmits, Radio A, 94A, iscapable of calculating the distance to Radio B, 94A.

[0124] Through periodic SYNC packets to radio C, 98A, and radio D, 96A,on the network, clock synchronization could be maintained throughout theentire network of radios. Assuming that radio A, 92A, radio B, 94A,radio C, 98A and radio D, 96A, always transmit packets at the immediatestart of their slot times 92B, 94B, 96B, and 98B, this system wouldallow all radios on a network to immediately calculate the distance toany other radio on the network whenever a radio transmitted a packet.

[0125] Exemplary Transceiver Implementation

[0126] Transmitter

[0127] An exemplary embodiment of an impulse radio transmitter 602 of animpulse radio communication system having one subcarrier channel willnow be described with reference to FIG. 6.

[0128] The transmitter 602 comprises a time base 604 that generates aperiodic timing signal 606. The time base 604 typically comprises avoltage controlled oscillator (VCO), or the like, having a high timingaccuracy and low jitter, on the order of picoseconds (ps). The voltagecontrol to adjust the VCO center frequency is set at calibration to thedesired center frequency used to define the transmitter's nominal pulserepetition rate. The periodic timing signal 606 is supplied to aprecision timing generator 608.

[0129] The precision timing generator 608 supplies synchronizing signals610 to the code source 612 and utilizes the code source output 614together with an internally generated subcarrier signal (which isoptional) and an information signal 616 to generate a modulated, codedtiming signal 618. The code source 612 comprises a storage device suchas a random access memory (RAM), read only memory (ROM), or the like,for storing suitable PN codes and for outputting the PN codes as a codesignal 614. Alternatively, maximum length shift registers or othercomputational means can be used to generate the PN codes.

[0130] An information source 620 supplies the information signal 616 tothe precision timing generator 608. The information signal 616 can beany type of intelligence, including digital bits representing voice,data, imagery, or the like, analog signals, or complex signals.

[0131] A pulse generator 622 uses the modulated, coded timing signal 618as a trigger to generate output pulses. The output pulses are sent to atransmit antenna 624 via a transmission line 626 coupled thereto. Theoutput pulses are converted into propagating electromagnetic pulses bythe transmit antenna 624. In the present embodiment, the electromagneticpulses are called the emitted signal, and propagate to an impulse radioreceiver 702, such as shown in FIG. 7, through a propagation medium,such as air, in a radio frequency embodiment. In a preferred embodiment,the emitted signal is wide-band or ultrawide-band, approaching amonocycle pulse as in FIG. 1A. However, the emitted signal can bespectrally modified by filtering of the pulses. This bandpass filteringwill cause each monocycle pulse to have more zero crossings (morecycles) in the time domain. In this case, the impulse radio receiver canuse a similar waveform as the template signal in the cross correlatorfor efficient conversion.

[0132] Receiver

[0133] An exemplary embodiment of an impulse radio receiver (hereinaftercalled the receiver) for the impulse radio communication system is nowdescribed with reference to FIG. 7.

[0134] The receiver 702 comprises a receive antenna 704 for receiving apropagated impulse radio signal 706. A received signal 708 is input to across correlator or sampler 710 via a receiver transmission line,coupled to the receive antenna 704, and producing a baseband output 712.

[0135] The receiver 702 also includes a precision timing generator 714,which receives a periodic timing signal 716 from a receiver time base718. This time base 718 is adjustable and controllable in time,frequency, or phase, as required by the lock loop in order to lock onthe received signal 708. The precision timing generator 714 providessynchronizing signals 720 to the code source 722 and receives a codecontrol signal 724 from the code source 722. The precision timinggenerator 714 utilizes the periodic timing signal 716 and code controlsignal 724 to produce a coded timing signal 726. The template generator728 is triggered by this coded timing signal 726 and produces a train oftemplate signal pulses 730 ideally having waveforms substantiallyequivalent to each pulse of the received signal 708. The code forreceiving a given signal is the same code utilized by the originatingtransmitter to generate the propagated signal. Thus, the timing of thetemplate pulse train matches the timing of the received signal pulsetrain, allowing the received signal 708 to be synchronously sampled inthe correlator 710. The correlator 710 ideally comprises a multiplierfollowed by a short term integrator to sum the multiplier product overthe pulse interval.

[0136] The output of the correlator 710 is coupled to a subcarrierdemodulator 732, which demodulates the subcarrier information signalfrom the subcarrier. The purpose of the optional subcarrier process,when used, is to move the information signal away from DC (zerofrequency) to improve immunity to low frequency noise and offsets. Theoutput of the subcarrier demodulator is then filtered or integrated inthe pulse summation stage 734. A digital system embodiment is shown inFIG. 7. In this digital system, a sample and hold 736 samples the output735 of the pulse summation stage 734 synchronously with the completionof the summation of a digital bit or symbol. The output of sample andhold 736 is then compared with a nominal zero (or reference) signaloutput in a detector stage 738 to determine an output signal 739representing the digital state of the output voltage of sample and hold736.

[0137] The baseband signal 712 is also input to a lowpass filter 742(also referred to as lock loop filter 742). A control loop comprisingthe lowpass filter 742, time base 718, precision timing generator 714,template generator 728, and correlator 710 is used to generate an errorsignal 744. The error signal 744 provides adjustments to the adjustabletime base 718 to time position the periodic timing signal 726 inrelation to the position of the received signal 708.

[0138] In a transceiver embodiment, substantial economy can be achievedby sharing part or all of several of the functions of the transmitter602 and receiver 702. Some of these include the time base 718, precisiontiming generator 714, code source 722, antenna 704, and the like.

[0139] FIGS. 8-10 illustrate the cross correlation process and thecorrelation function. FIG. 8 shows the waveform of a template signal.FIG. 8B shows the waveform of a received impulse radio signal at a setof several possible time offsets. FIG. 9 represents the output of thecorrelator (multiplier and short time integrator) for each of the timeoffsets of FIG. 8B. Thus, this graph does not show a waveform that is afunction of time, but rather a function of time-offset. For any givenpulse received, there is only one corresponding point which isapplicable on this graph. This is the point corresponding to the timeoffset of the template signal used to receive that pulse. Furtherexamples and details of precision timing can be found described in U.S.Pat. No. 5,677,927, and commonly owned co-pending application Ser. No.09/146,524, filed Sep. 3, 1998, titled “Precision Timing GeneratorSystem and Method”, both of which are incorporated herein by reference.

[0140] Impulse Radio as Used in the Present Invention

[0141] Utilizing the unique properties of impulse radio, the currentstate of the art in positioning systems is dramatically improved. Byusing the positioning techniques in the prior impulse radio positioningpatents which have been incorporated by reference, as well as theaforementioned novel positioning TDMA technique, in the followingarchitectures, novel impulse radio positioning systems and methods areherein enabled.

Synchronized Transceiver Tracking

[0142]FIG. 10 illustrates a Synchronized Transceiver Tracking, wherein anetwork of fixed-location reference transceivers (two-way impulseradios) allow the position of multiple mobile transceivers (two-wayimpulse radios) to be determined. This architecture is perhaps the mostgeneric of the impulse radio geo-positioning architectures since boththe mobile and reference radios are full two-way transceivers. Thenetwork is designed to be scalable, allowing from very few reference andmobile radios to a very large number.

[0143]FIG. 10 is a block diagram showing a simple implementation of thisarchitecture. This particular example shows a system of four referenceradios (R1, 1002, through R4, 1008) and two mobile radios (M1, 1012, andM2, 1010). The arrows between the radios represent two-way data and/orvoice links. A fully inter-connected network would have every radiocontinually communicating with every other radio, but this is notrequired and can be dependent upon the needs of the particularapplication.

[0144] Each radio is a two-way transceiver; thus each link betweenradios is two-way (duplex). Precise ranging information (the distancebetween two radios) is distributed around the network in such a way asto allow the mobile radios (M1, 1012, and M2, 1010, in FIG. 10) todetermine their precise three-dimensional position within a localcoordinate system. This position, along with other data or voicetraffic, can then be relayed from the mobile radios back to thereference master radio (R1, 1002), one of the other reference relayradios (R2, 1004, through R4, 1008 in FIG. 10), or to other mobileradios such as M2, 1010, in FIG. 10).

[0145] The radios used in this architecture are impulse radio two-waytransceivers. The reference and mobile radio hardware is essentially thesame. The firmware, however, vanres slightly based on the functions eachradio must perform. For example, R1, 1002, can designate as thereference master radio. As the master, it directs the passing ofinformation and typically will be responsible for collecting all thedata for external graphical display. The remaining reference relayradios contain a separate version of the firmware, the primarydifference being the different parameters or information that eachreference relay radio must provide the network. Finally, the mobileradios have their own firmware version that calculates their positionand displays it locally if desired.

[0146] In FIG. 10, each radio link is a two-way link that allows for thepassing of information, both data and/or voice. The data-rates betweeneach radio link is a function of several variables including the numberof pulses integrated to get a single bit, the number of bits per dataparameter, the length of any headers required in the messages, the rangebin size, and the number of radios in the network.

[0147] By transmitting in assigned time slots and by carefully listeningto the other radios transmit in their assigned transmit time slots, theentire group of radios within the network, both mobile and reference,will be able to synchronize themselves. The oscillators used on theimpulse radio boards will drift slowly in time, thus requiring continualmonitoring and adjustment of synchronization. The accuracy of thissynchronization process (timing) is dependent upon several factors.These factors include how often and how long each radio transmits.

[0148] The purpose of the impulse radio geo-positioning network is to beable to track mobile radios. Tracking is accomplished by steppingthrough several well-defined steps. The first step is for the referenceradios to synchronize together and begin passing information. Then, whena mobile radio enters the network area, it synchronizes itself to thepreviously synchronized reference radios. Once the mobile radio issynchronized, it begins collecting and time-tagging range measurementsfrom any available reference (or other mobile) radio. The mobile radiothen takes these time-tagged ranges and, using a least squares-based orsimilar estimator, calculates the mobile radio position in localcoordinates. If the situation warrants and the conversion possible, thelocal coordinates can be converted to any one of the worldwidecoordinates such as Earth Centered Inertial (ECI), Earth Centered EarthFixed (ECEF), or J2000 (inertial coordinates fixed to year 2000).Finally, the mobile radio forwards its position solution to thereference master radio for storage and real-time display.

Unsynchronized Transceiver Tracking

[0149]FIG. 11 illustrates Unsynchronized Transceiver Tracking, which isa network of fixed-location, unsynchronized reference impulse radiotransceivers, 1102-1108, which allows the position of multiple mobileimpulse radio transceivers, 1110 and 1112, to be determined. Thisarchitecture is similar to Synchronized Transceiver Tracking of FIG. 10,except that the reference receivers are not time-synchronized. Both themobile and reference radios for this architecture are full two-waytransceivers. The network is designed to be scalable, allowing from veryfew reference and mobile radios to a very large number of both.

[0150] This particular embodiment of FIG. 11 shows a system of fourreference radios (R1, 1102 through R4, 1108) and two mobile radios (M1,1110 and M2, 1112). The arrows between the radios represent two-way dataand/or voice links. A fully inter-connected network would have everyradio continually communicating with every other radio, but this is notrequired and can be defined as to the needs of the particularapplication. Each radio is a two-way transceiver; thus each link betweenradios is two-way (duplex). Precise ranging information (the distancebetween two radios) is distributed around the network in such a way asto allow the mobile radios (M1, 1110 and M2, 1112 in FIG. 11) todetermine their precise three-dimensional position within a localcoordinate system. This position, along with other data or voicetraffic, can then be relayed from the mobile radios back to thereference master radio (R1, 1102), one of the other reference relayradios (R2, 1104 through RN), or to other mobile radios.

[0151] The radios used in the architecture of FIG. 11 are impulse radiotwo-way transceivers. The reference and mobile radio hardware isessentially the same. The firmware, however, varies slightly based onthe functions each radio must perform. For example, R1, 1102, isdesignated as the reference master radio. It directs the passing ofinformation, and typically will be responsible for collecting all thedata for external graphical display. The remaining reference relayradios contain a separate version of the firmware, the primarydifference being the different parameters or information that eachreference relay radio must provide the network. Finally, the mobileradios have their own firmware version that calculates their positionand displays it locally, if desired.

[0152] Each radio link is a two-way link that allows for the passing ofinformation, data and/or voice. The data-rates between each radio linkis a function of several variables including the number of pulsesintegrated to get a single bit, the number of bits per data parameter,the length of any headers required in the messages, the range bin size,and the number of radios in the network.

[0153] Unlike the radios in the Synchronized Transceiver Trackingarchitecture, the reference radios in this architecture are nottime-synchronized as a network. These radios simply operateindependently (free-running), providing ranges to the mobile radioseither periodically, randomly, or when tasked. Depending upon theapplication and situation, the reference radios may or may not talk toother reference radios in the network.

[0154] As with the architecture of FIG. 10, the purpose of the impulseradio geo-positioning network is to be able to track mobile radios.Tracking is accomplished by stepping through several steps. These stepsare dependent upon the way in which the reference radios range with themobile radios (periodically, randomly, or when tasked). When a mobileradio enters the network area, it either listens for reference radios tobroadcasts, then responds, or it queries (tasks) the desired referenceradios to respond. The mobile radio begins collecting and time-taggingrange measurements from reference (or other mobile) radios. The mobileradio then takes these time-tagged ranges and, using a leastsquares-based or similar estimator, calculates the mobile radio positionin local coordinates. If the situation warrants and the conversionpossible, the local coordinates can be converted to any one of theworldwide coordinates such as Earth Centered Inertial (ECI), EarthCentered Earth Fixed (ECEF), or J2000 (inertial coordinates fixed toyear 2000). Finally, the mobile radio forwards its position solution tothe reference master radio for storage and real-time display if desired,1114.

Synchronized Transmitter Tracking

[0155] In Synchronized Transmitter Tracking, a network of fixed-locationtwo way reference impulse radio transceivers allow the position ofmultiple mobile impulse radio transmitters to be determined. Thisarchitecture is perhaps the simplest of the impulse radiogeo-positioning architectures, from the point-of-view of the mobileradio, since the mobile radios simply transmits in a free-running sense.The network is designed to be scalable, allowing from very few referenceand mobile radios to a very large number. This architecture isespecially applicable to an “RF tag” (radio frequency tag) type ofapplication.

[0156]FIG. 12 is a block diagram showing a simple implementation of thisarchitecture. This particular example shows a system of four referenceradios (R1,1202 through R4, 1208) and two mobile radios (M1,1210 and M2,1212). The arrows between the radios represent two-way and one-way dataand/or voice links. Notice that the mobile impulse radios only transmit,thus they do not receive the transmissions from the other mobile radios.

[0157] Each reference radio is a two-way transceiver; thus each linkbetween reference radios is two-way (duplex). Precise ranginginformation (the distance between two radios) is distributed around thereference radio network in such a way as to allow the synchronizedreference radios to receive the mobile radio transmissions (M1 and M2 inFIG. 1) in order to determine the mobile radio precise three-dimensionalposition within a local coordinate system. This position, along withother data or voice traffic, can then be relayed from the referencerelay radios back to the reference master radio (R1).

[0158] The reference radios used in this architecture are impulse radiotwo-way transceivers, the mobile impulse radios are one-waytransmitters. The firmware in the radios varies slightly based on thefunctions each radio must perform. For example, R1, 1202, is designatedas the reference master radio. It directs the passing of information,and typically will be responsible for collecting all the data forexternal graphical display. The remaining reference relay radios containa separate version of the firmware, the primary difference being thedifferent parameters or information that each reference relay radio mustprovide the network. Finally, the mobile radios have their own firmwareversion that transmits pulses in predetermined sequences.

[0159] Each reference radio link is a two-way link that allows for thepassing of information, data and/or voice. The data-rates between eachradio link is a function of several variables including the number ofpulses integrated to get a single bit, the number of bits per dataparameter, the length of any headers required in the messages, the rangebin size, and the number of radios in the network.

[0160] By transmitting in assigned time slots and by carefully listeningto the other radios transmit in their assigned transmit time slots, theentire group of reference radios within the network will be able tosynchronize themselves. The oscillators used on the impulse radio boardswill drift slowly in time, thus requiring continual monitoring andadjustment of synchronization. The accuracy of this synchronizationprocess (timing) is dependent upon several factors. These factorsinclude how often and how long each radio transmits along with otherfactors. The mobile radios, since they are transmit-only transmitters,are not time-synchronized to the synchronized reference radio network.

[0161] The purpose of the impulse radio geo-positioning network is to beable to track mobile radios. Tracking is accomplished by steppingthrough several well-defined steps. The first step is for the referenceradios to synchronize together and begin passing information. Then, whena mobile radio enters the network area and begins to transmit pulses,the reference radios pick up these pulses as time-of-arrivals (TOAs).Multiple TOAs collected by different synchronized reference radios arethen converted to ranges, which are then used to calculate mobile radioXYZ position in local coordinates. If the situation warrants and theconversion possible, the local coordinates can be converted to any oneof the worldwide coordinates such as Earth Centered Inertial (ECI),Earth Centered Earth Fixed (ECEF), or J2000 (inertial coordinates fixedto year 2000).

Unsynchronized Transmitter Tracking

[0162] In Unsynchronized Transmitter Tracking, a network offixed-location impulse radio reference transceivers allow the positionof multiple mobile impulse radio transmitters to be determined. Thisarchitecture is very similar to the Synchronized Transmitter Trackingarchitecture except that the reference radios are not synchronized intime. In other words, both the reference radios and the mobile radiosare free-running. The network is designed to be scalable, allowing fromvery few reference and mobile radios to a very large number. Thisarchitecture is especially applicable to an “RF tag” type ofapplication.

[0163]FIG. 13 is a block diagram showing a simple implementation of thisarchitecture. This particular embodiment shows a system of fourreference radios (R1, 1302 through R4, 1308) and two mobile radios (M1,1310 and M2, 1312). The arrows between the radios represent two-way andone-way data and/or voice links. Notice that the mobile radios onlytransmit, thus they do not receive the transmissions from the othermobile radios. Unlike the Synchronous Transmitter Tracking architecture,the reference radios in this architecture are free-running(unsynchronized). There are several ways to implement this design, themost common involves relaying the time-of-arrival (TOA) pulses from themobile and reference radios, as received at the reference radios, backto the reference master radio.

[0164] Each reference radio in this architecture is a two-way impulseradio transceiver; thus each link between reference radios can be eithertwo-way (duplex) or one-way (simplex). TOA information will typically betransmitted from the reference radios back to the reference master radiowhere the TOAs will be converted to ranges and then XYZ position, whichcan then be displayed, 1314.

[0165] The reference radios used in this architecture are impulse radiotwo-way transceivers, the mobile radios are one-way impulse radiotransmitters. The firmware in the radios varies slightly based on thefunctions each radio must perform. For example, R1, 1302 is designatedas the reference master radio. It. collects the TOA information, andtypically will be responsible for forwarding tracking data for externalgraphical display, 1314. The remaining reference relay radios contain aseparate version of the firmware, the primary difference being thedifferent parameters or information that each reference relay radio mustprovide the network. Finally, the mobile radios have their own firmwareversion that transmits pulses in predetermined sequences.

[0166] Each reference radio link is a two-way link that allows for thepassing of information, data and/or voice. The data-rates between eachradio link is a function of several variables including the number ofpulses integrated to get a single bit, the number of bits per dataparameter, the length of any headers required in the messages, the rangebin size, and the number of radios in the network.

[0167] Since the reference radios and mobile radios are free-running,synchronization is actually done by the reference master impulse radio1302 alone. The oscillators used in the impulse radios will drift slowlyin time, thus likely requiring continual monitoring and adjustment ofsynchronization at the reference master radio. The accuracy of thissynchronization (timing) is dependent upon several factors. Thesefactors include how often and how long each radio transmits along withother factors.

[0168] The purpose of the impulse radio geo-positioning network is to beable to track mobile radios. Tracking is accomplished by steppingthrough several steps. The most likely method is to have each referenceradio periodically (randomly) transmit a pulse sequence. Then, when amobile radio enters the network area and begins to transmit pulses, thereference radios pick up these pulses as time-of-arrivals (TOAs) as wellas the pulses (TOAs) transmitted by the other reference radios. TOAs canthen either be relayed back to the reference master radio or justcollected directly (assuming it can pick up all the transmissions). Thereference master radios then converts these TOAs to ranges, which arethen used to calculate mobile radio XYZ position in local coordinates.If the situation warrants and the conversion possible, the localcoordinates can be converted to any one of the worldwide coordinatessuch as Earth Centered Inertial (ECI), Earth Centered Earth Fixed(ECEF), or J2000 (inertial coordinates fixed to year 2000).

Synchronized Receiver Tracking

[0169] In Synchronized Receiver Tracking, a network of fixed-locationreference impulse radio transceivers allow the position of multipleimpulse radio mobile receivers to be determined. This architecture isdifferent from the Synchronized Transmitter Tracking architecture inthat in this design the mobile receivers will determine their positionsbut will not be broadcasting it to anyone (since they are receive-onlyradios). The network is designed to be scalable, allowing from very fewreference and mobile radios to a very large number of both.

[0170]FIG. 14 is a block diagram showing a simple implementation of thisarchitecture. This particular example shows a system of four referenceradios (R1, 1402 through R4, 1408) and two mobile radios (M1, 1410 andM2, 1412). The arrows between the radios represent two-way and one-waydata and/or voice links. Notice that the mobile radios only receivetransmissions from other radios, and do not transmit.

[0171] Each reference radio is a two-way transceiver, each mobile radiois a receive-only radio. Precise, synchronized pulses are transmitted bythe reference network and received by the other reference radios and themobile radios. The mobile radios takes these times-of-arrival (TOA)pulses, converts them to ranges, then determines its XYZ position. Sincethe mobile radios do not transmit, only they themselves will know theirXYZ position.

[0172] The reference radios used in this architecture are impulse radiotwo-way transceivers, the mobile radios are receive-only radios. Thefirmware for the radios varies slightly based on the functions eachradio must perform. For example, R1, 1402 is designated as the referencemaster radio. It directs the synchronization of the reference radionetwork. The remaining reference relay radios contain a separate versionof the firmware, the primary difference being the different parametersor information that each reference relay radio must provide the network.Finally, the mobile radios have their own firmware version thatcalculates their position and displays it locally if desired.

[0173] Each reference radio link is a two-way link that allows for thepassing of information, data and/or voice. The mobile radios arereceive-only. The data-rates between each radio link is a function ofseveral variables including the number of pulses integrated to get asingle bit, the number of bits per data parameter, the length of anyheaders required in the messages, the range bin size, and the number ofradios in the network.

[0174] By transmitting in assigned time slots and by carefully listeningto the other reference radios transmit in their assigned transmit timeslots, the entire group of reference radios within the network will beable to synchronize themselves. The oscillators used on the impulseradio boards will drift slowly in time, thus requiring continualmonitoring and adjustment of synchronization. The accuracy of thissynchronization (timing) is dependent upon several factors. Thesefactors include how often and how long each radio transmits along withother factors.

[0175] The purpose of the impulse radio geo-positioning network is to beable to track mobile radios. Tracking is accomplished by steppingthrough several well-defined steps. The first step is for the referenceradios to synchronize together and begin passing information. Then, whena mobile radio enters the network area, it begins receiving thetime-of-arrival (TOA) pulses from the reference radio network. These TOApulses are converted to ranges, then the ranges are used to determinemobile radio XYZ position in local coordinates using a leastsquares-based estimator. If the situation warrants and the conversionpossible, the local coordinates can be converted to any one of theworldwide coordinates such as Earth Centered Inertial (ECI), EarthCentered Earth Fixed (ECEF), or J2000 (inertial coordinates fixed toyear 2000). Finally, the mobile radio forwards its position solution tothe reference master radio for storage and real-time display.

Unsynchronized Receiver Tracking

[0176] In Unsynchronized Receiver Tracking, a network of fixed-locationreference impulse radio transceivers allow the position of multipleimpulse radio mobile receivers to be determined. This architecture isdifferent from the Synchronized Receiver Tracking architecture in thatin this design the reference radios are not time-synchronized. Similarto the Synchronized Receiver Tracking architecture, mobile receive-onlyradios will determine their positions but will not be broadcasting it toanyone (since they are receive-only radios). The network is designed tobe scalable, allowing from very few reference and mobile radios to avery large number of both.

[0177]FIG. 15 is a block diagram showing a simple implementation of thisarchitecture. This particular example shows a system of four referenceradios (R1, 1502 through R4, 1508) and two mobile radios (M1, 1510 andM2, 1512). The arrows between the radios represent two-way and one-waydata and/or voice links. Notice that the mobile radios only receivetransmissions from other radios, and do not transmit.

[0178] Each reference radio is an impulse radio two-way transceiver,each mobile radio is a receive-only impulse radio. Precise,unsynchronized pulses are transmitted by the reference network andreceived by the other reference impulse radios and the mobile impulseradios. The mobile radios takes these times-of-arrival (TOA) pulses,converts them to ranges, then determines its XYZ position. Since themobile impulse radios do not transmit, only they themselves will knowtheir XYZ position.

[0179] The impulse radio reference radios used in this architecture areimpulse radio two-way transceivers, the mobile radios are receive-onlyradios. The firmware for the radios varies slightly based on thefunctions each radio must perform. For this design, the reference masterradio may be used to provide some synchronization information to themobile radios or the mobile radio itself (knowing the XYZ for eachreference radio) may do all of the synchronization internally.

[0180] The data-rates between each radio link is a function of severalvariables including the number of pulses integrated to get a single bit,the number of bits per data parameter, the length of any headersrequired in the messages, the range bin size, and the number of impulseradios in the network.

[0181] For this architecture, the reference radios transmit in afree-running (unsynchronized) manner. The oscillators used on theimpulse radio boards will drift slowly in time, thus requiring continualmonitoring and adjustment of synchronization by the reference masterradios or the mobile radio (whomever is doing the synchronization). Theaccuracy of this synchronization (timing) is dependent upon severalfactors. These factors include how often and how long each radiotransmits along with other factors.

[0182] The purpose of the impulse radio geo-positioning network is to beable to track mobile radios. Tracking is accomplished by steppingthrough several steps. The first step is for the reference radios tobegin transmitting pulses in a free-running (random) manner. Then, whena mobile radio enters the network area, it begins receiving thetime-of-arrival (TOA) pulses from the reference radio network. These TOApulses are converted to ranges, then the ranges are used to determinemobile radio XYZ position in local coordinates using a leastsquares-based estimator. If the situation warrants and the conversionpossible, the local coordinates can be converted to any one of theworldwide coordinates such as Earth Centered Inertial (ECI), EarthCentered Earth Fixed (ECEF), or J2000 (inertial coordinates fixed toyear 2000). Finally, the mobile radio forwards its position solution tothe reference master radio for storage and real-time display 1514.

[0183] For ease of reference, in the following diagrams the below legendapplies.

Symbols and Definitions

[0184]  Receiver Radio (receive only)

[0185] X Transmitter Radio (transmit only)

[0186]

Transceiver Radio (receive and transmit)

[0187] R_(i) Reference Radio (fixed location)

[0188] M_(i) Mobile Radio (radio being tracked)

[0189]

Duplex Radio Link

[0190]

Simplex Radio Link

[0191] TOA, DTOA Time of Arrival, Differenced TOA

[0192]FIG. 16 shows a Mixed Mode Reference Radio architecture. Thisarchitecture defines a reference network comprised of any combination oftransceivers (R₁, R₂, R₄, R₅), transmitters (R₃), and receivers (R₆).Mobile radios entering this mixed-mode reference network will then usewhatever reference radios are appropriate.

[0193]FIG. 17 describes a mixed mode architecture with a combination oftransceivers, transmitters and receivers. Herein, the mobile impulseradios 1712, 1710, 1714 are the mixed mode and the reference impulseradios 1702, 1704, 1706 and 1708 are likely time-synched. In thisillustrative example, the mobile radio 1712 is a transmitter only, 1714is a receiver only and 1710 is a transceiver. The determination of themix of mobile impulse radios and reference radios will be determined bysystem requirements. For example, in the Disney World example the Parkmay want to rent out one device to customers that can locate a child iflost, another to help the customer find bathrooms and roller coasters orboth; and the reference radios must work with both types of mobileimpulse radio systems.

[0194] As detailed above and in the referenced patent applications, asteerable null antennae can be used with impulse radio distancecalculations. By using the example architecture of FIG. 18, a system canbe implemented to take advantage of this distance measuring usingsteerable null antennae. Herein, all of the reference radios 1802, 1804,1806 and 1808 or some of them can utilize steerable null antenna designsto direct the impulse propagation; with one important advantage beingthe possibility of using fewer impulse radios or improving range andpower requirements. The mobile impulse radio transceiver 1810 can alsouse a steerable null antenna for most architectures.

[0195]FIG. 19 illustrates the possibility of using specialized antennaearchitectures. Impulse radios 1902, 1904, 1906 and 1908 of thisarchitecture may use a difference antenna analogous to the phasedifference antenna used in GPS carrier phase surveying. The referenceradios should be time synched and the mobile radio 1910 herein cantransmit and receive. Again, it should be noted that in this, as allarchitectures, the number of radios is for illustrative purposes onlyand more than one mobile impulse radio can be implemented in the presentarchitecture.

[0196]FIG. 20 illustrates a specialized antennae architecture whereindirectional antennae are used and wherein the reference impulse radios1902, 1904, 1906 and 1908 are time synched. As with the steerable nullantennae design, the implementation of this architecture will be drivenby design requirements. Also, herein the mobile impulse radiotransceiver 1910 can be use a directional antennae.

[0197]FIG. 21 illustrates amplitude sensing architectures whereinamplitude sensing is used for tracking and positioning. Herein,reference radios 2002, 2004, 2006 and 2008 are likely time-synched.Instead of measuring range using TOA methods (round-trip pulseintervals), signal amplitude is used to determine range. Severalimplementations can be used such as measuring the “absolute” amplitudeand comparing to pre-defined look up table that relates range toamplitude, or “relative” amplitude where pulse amplitudes from separateradios are differenced.

[0198] In addition to position locating within an impulse radio network,impulse radios can be used to augment existing positioning systems toimprove on these systems or to broaden potential coverage areas forimpulse radio systems. FIG. 22 illustrates an impulse radio navigationaugmentation architecture for augmentation of Global Positioning Systems(GPS). Impulse radios 2204 and 2206 would be used to augment stand-aloneGPS receivers. Impulse radio measurements (range, doppler, TOA, etc.)can be used to provide both additional accuracy and better geometry inparticular cases. For example, GPS₁, 2202 might be in the clear whileGPS₂, 2208, would be in foliage. GPS₁, 2202 could provide bothdifferential GPS (DGPS) corrections and impulse measurements to GPS₂,2208 to improve GPS₂, accuracy.

[0199]FIG. 23 illustrates GPS/INS augmentation in navigationaugmentation architectures 2300. Herein impulse radios 2304 and 2306would be used to augment GPS/INS (inertial navigation system) units.Impulse radio measurements (range, doppler, TOA, etc.) can be used toprovide both additional accuracy and better geometry in particularcases. Herein impulse radio 2304 could provide impulse radiomeasurements to the GPS/INS 2302 to improve accuracy.

[0200] Not only GPS and GPS/INS derive benefits from integrating withimpulse radios, generic navigation sensors can be augmented 2400 aswell. Impulse radios 2404 can be interfaced with various navigationsystems such as electro-optical, LORAN, LASER, LfDAR, radar, SAR, VOR,DME, magnetic compasses etc. Impulse radio measurements (range, doppler,TOA, etc.) can be used to provide additional accuracy and bettergeometry in particular cases. Herein, impulse radio 2206 wouldcommunicate with impulse radio 2404 which as mentioned is interfacedwith the navigation system.

[0201] Using the properties associated with impulse radio technology inone of the aforementioned architectures and with the distance andpositioning techniques herein articulated and in the patentsincorporated herein by reference, the following impulse radio mobileposition locating system and method is used in building environment2500. Further, the system and method herein provides for the positionlocating to be mobile and capable of locating persons in an environmentsuch as firefighters in a burning building. Because fire departmentsdon't know in which buildings fires are going to occur, they must beable to implement the system on the fly. FIG. 25 shows building 2502where a fire or other emergency may be taking place (an example ofanother emergency may be policeman knowing the locating of officers in abuilding with hostages). Firemen #1, 2518, in this embodiment ispositioned in the upper left portion of building 2502. Fireman #2, 2504,is located on the second floor towards the right portion of the building2502.

[0202] Upon arrival at the building, mobile impulse radios 2516, 2514and 2512 are positioned around the building 2502. Two of the referenceradios are positioned in pre-designated areas 2528 and 2530 that wereascertained during the initial setup. This enables positioning relativeto the building schematic and overlay. In order to get three dimensionallocating, a fourth impulse radio receiver 2506 is located non-coplanerto the rest of the impulse radios location such as on top of the firetruck ladder 2508 connected to fire truck 2510. Located inside of firetruck 2510 is a computer with monitor 2520 (shown blown up as 2522). Thecomputer with monitor has preprogrammed into it an overlay of aschematic or blue print of the building for which the fire is located. Agiven fire department is typically responsible for a given area and willhave already programmed the information in to the computer and when afire is determined to be present the address is typed in and an overlayof the building is displayed.

[0203] By using one of the of architectures illustrated above, theposition of firefighter #1, 2518, and firefighter #2, 2504 can bedetermined. Since buildings and scenarios vary widely from firedepartment to fire department, the best suited architecture will be on acase by case basis. In the current illustration, the architecture ofFIG. 10 is used. Once the reference radios are set up, reference radio2514 talks to reference radios 2516, 2512, 2506 and fireman #1, 2518mobile impulse radio and fireman #2, 2514 impulse radio. Similarly therest of the impulse radios synch to each other and the fireman radios.In this case, since the fireman's 2518 and 2504 mobile impulse radiosare impulse radio transceivers, they can have two way communications andcan also be interfaced with a sensor to relate information to themonitor outside such as temperature or the fireman's heart rate. This isone of the truly unique characteristics of impulse radio: the dualfunctionality relating to positioning and communications in one impulseradio.

[0204] The information can be processed in impulse radio 2512 or it canbe done in computer 2522. The computer 2522 processes the informationand puts the information into displayable form by taking the blue printor schematic and positioning information and displaying the position offireman #1, 2518 as shown at 2524 and fireman #2, 2504, as shown in2526.

[0205]FIG. 26 at 2600 illustrates in a block diagram the informationreceived by processor 2608 located in computer 2520. The processor 2608receives position information 2602 from fireman #1, 2518, who isconnected to impulse radio #1. Processor 2608 also receives informationfrom fireman #2, 2504, connected to impulse radio #2, wherein bothimpulse radios attached to the fireman are in communication with allreference impulse radios wherein the positioning is determined. At 2600it is illustrated that N possible fireman can be located within thebuilding 2502 and there positions can also be determined. As mentioned,the processor 2608 can receive information 2610 and 2614 from bothfireman's impulse radio transceivers concerning temperature where thefireman are at. Again, N different parameters can be sensed and passedto be displayed as shown at 2614.

[0206] The processor takes the above positioning and sensed informationand the information concerning the layout of the building 2606 anddisplays the information on display 2616. Although a display isillustrated, it is understood that the information could be interfacedwith a variety of monitoring devices. For example, the fireman's heartrate can be displayed on heart rate monitor thus determining in verysevere cases whether or not the fireman is under sever stress or evenalive.

[0207] Only slight modifications to this burning building example wouldbe required to implement the above system in the aforementioned prisonenvironment. As with the firefighters, the prison guards would carry themobile radio with them and with the incorporation of one of the abovearchitectures can use the mobile device to communicate with othermonitoring prison guards. There would likely not be a requirement forthe reference radios to be portable as they could be hard wired andlocal AC powered. Further, the same mobile impulse radio would be usedwithin the defined reference radio area (i.e., the prison), and couldthereby provide exact location information. Also, if the prison guardwere in potential danger, an alerting means could be used and thedispatch of additional security personnel could be dispatched to thedistressed guards location immediately.

[0208]FIG. 27 illustrates the impulse radio position system and methodas used in an environment such as a DisneyLand resort. Reference impulseradio transceivers 2702, 2704, 2706, 2708, 2710, 2712, 2714, 2716 and2718 are positioned for maximum coverage throughout the park and are inknown reference positions. Note the severe multipath characteristics ofa theme part such as this: trees, metal rides and metal buildings. Sincethe area to be covered is not variable as in the burning buildingscenario, the reference impulse radios can be either in communicationwith each other via wired or wireless means. Depending on therequirements of the park, many of the above architectures can beutilized. For example, if the theme park desires that every child beable to be located, the requirements for long battery life andinexpensive impulse radio are required. Thus an architecture like 14Awould be a good match, where the mobile impulse radio receiver is just atransmitter (i.e., low cost and very inexpensive) and the referenceradios are all in synch (easily done if all radios are hardwired or evenif communicating via wireless impulse radio transmissions). If the themepark wanted to provide emergency personnel at the park a device thatwould show the where to go immediately and cost was less of a concern,then the architecture illustrated in FIG. 14B would be used. Herein, themobile impulse radio could provide them with their location and showthem how to get to the emergency. Also, again due to the uniqueproperties of impulse radio, communications could be accomplished withthe impulse mobile radio.

[0209] In the lost child example, stations 2720 and 2722 could be set upfor locating the child when lost. The mobile impulse radio associatedwith the child and his parents is stored in the computer at the time ofissue. When lost, the parents can go to station 2720 or 2722 and informthem of the child's name and request they activate the display for thatchild. As with the burning building example, an overlay of the park isin the computer memory and provides a visual display 2724 of thelocation of the child.

[0210]FIG. 28 is flow chart of the process of child location of FIG. 27.Although the process herein is specific to a theme park, the process canalso be employed in any area that can be bound by impulse radioreference radios either alone or in conjunction with other positioningsystems such as GPS. The first step is to equip the theme park withreference impulse radios 2802. In this embodiment the radios are fixedand the positioning of them is contingent of the RF propagationenvironment of each area of the theme park. For example, if there is anarea densely populated with trees or metal buildings, placement of thereference impulse radios would be closer together. Further, setting theintegration amount of the pulses would be done based on the RFpropagation environment and the information required. If it is a highlycluttered RF environment, larger integration per data bit is required.The method of accomplishing this is articulated in the patentsincorporated herein by reference.

[0211] In step 2804, each child entering the theme park is given amobile impulse radio. When the child is given the radio their name isassociated with the serial number of the mobile impulse radio they aregiven. The parents or guardians can place the transmitter on the childdirectly, in a stroller, in a stuffed bear given to the child as theyenter or any other method as desired. Once the mobile impulse radio hasbeen given to the child, it is activated and begins communication withthe reference impulse radios, thereby keeping track of the position ofthe child at all time within the park 2806. For privacy concerns andissues of capacity, the display portion of the child's tracking can beset so as not to activate until a report has been received that thechild is missing or if they are no longer in the coverage area. It isnoted that the mobile impulse radio is not required to be incommunication with all reference impulse radios simultaneously, as longas it is in communication with at least one of the reference impulseradios, positioning can be determined.

[0212] In step 2808, a determination is made if the child is lost in thepark or has left the park. When the system notices that the child'smobile impulse radio is no longer in communication with the referenceimpulse radios, an alert is given and last known position is displayed.The theme park can at that time take actions deemed appropriate. If theparent loses the child in step 2810 they can immediately go to alocation station and inform the attendants of the child's name. Uponentry of the name into the database, the position of the mobile impulseradio is given and thus the corresponding child's location. The mobileimpulse radio can be designed to be very inexpensive and therefore bethrown away after use. In step 2812, if no lost child condition exists,then the parents or guardians return the mobile impulse radio to thetheme park attendants, whereafter the transmission is deactivated andremoved from the tracking system and thrown away or batteries rechargedfor subsequent use.

[0213] While the above system assumes the mobile impulse radio positionis of concern to other than the person or object with which it isassociated, it may be the case that the person or object associated withthe mobile impulse radio is concerned with its/their location. This canbe accomplished readily by implementation of one of the architecturesherein articulated.

[0214]FIG. 29 illustrates the impulse radio position locating system andmethod in a warehouse environment 2900. In a warehouse, it is veryimportant many times to know exactly where various cargo and pallets ofthings are stored. Further, the multipath effects in a warehouse can bevery pronounced and therefore ideal for impulse radio advantages. Sinceitems may be stored for long periods of time and the synching of thereference impulse radios 2902, 2904, 2906 and 2908 can easily beaccomplished via wired or wireless means the architecture of FIG. 14Bwould be effective. In FIG. 29 each item stored 2912-2930 is associatedwith an impulse radio transmitter. Again, the impulse radio is atransmitter because long battery life is desired and the item in thiscase is assumed not to be concerned with where it is located. Incommunication with reference impulse radio 2906 is a computer 2932. Anoverlay of the warehouse is located in the computers memory along withthe relative position of the reference radios and thereby can display tothe user exactly which item is where in the warehouse.

[0215] While particular embodiments of the invention have beendescribed, it will be understood, however, that the invention is notlimited thereto, since modifications may be made by those skilled in theart, particularly in light of the foregoing teachings. It is, therefore,contemplated by the appended claims to cover any such modifications thatincorporate those features or those improvements which embody the spiritand scope of the present invention.

What is claimed is:
 1. A method of position location utilizing impulseradio means, comprising the steps of: transmitting an impulse radiosignal; and receiving said transmitted impulse radio signal, whereby theposition of said received signal is determined.
 2. System for positionlocation utilizing impulse radio means, comprising: at least onereference impulse radio means; and at least one mobile impulse radiomeans in communication with said at least one reference radio means,whereby position information of said mobile impulse radio means relativeto said at least one reference impulse radio means is provided.
 3. Thesystem for person or object position location utilizing Impulse Radio ofclaim 2, further comprising display means in communication with said atleast one reference radio for displaying position information of said atleast one mobile impulse radio relative to said at least one referenceimpulse radio.
 4. The system for person or object position locationutilizing Impulse Radio of claim 2, further comprising display means incommunication with said at least one mobile impulse radio for displayingposition information of said at least one mobile impulse radio relativeto said at least one reference impulse radio.
 5. The system for personor object position location utilizing Impulse Radio of claim 3, whereinsaid display means displays said position information of said at leastone mobile radio relative to said at least one reference impulse radioon an overlay of a depiction of the environment in which the referenceimpulse radio and the mobile impulse radio are located.
 6. The systemfor person or object position location utilizing Impulse Radio of claim4, wherein said display means displays said position information of saidat least one mobile radio relative to said at least one referenceimpulse radio on an overlay of a depiction of the environment in whichthe reference impulse radio and the mobile impulse radio are located. 7.System for person or object position location utilizing Impulse Radio,comprising: a plurality of reference impulse radios; at least one mobileimpulse radio in communication with available said plurality ofreference impulse radios, said communication providing positioninformation of said mobile impulse radio relative to said plurality ofsaid reference impulse radios.
 8. The system for person or objectposition location utilizing Impulse Radio of claim 7, further comprisinga display means, said display means displaying the position of said atleast one mobile impulse radio relative to said plurality of saidreference impulse radios.
 9. The system for person or object positionlocation utilizing Impulse Radio of claim 7, wherein said plurality ofreference impulse radios are transceivers and in duplex communicationwith each other and said at least one mobile impulse radio is an atleast one impulse radio transceiver in duplex communication with saidplurality of said reference impulse radios or with another at least onemobile impulse radio.
 10. The system for person or object positionlocation utilizing Impulse Radio of claim 7, wherein said plurality ofreference impulse radios are transceivers and not in communication witheach other and said at least one mobile impulse radio is an at least oneimpulse radio transceiver in duplex communication with each referenceimpulse radio available.
 11. The system for person or object positionlocation utilizing Impulse Radio of claim 7, wherein said plurality ofreference impulse radios direct simplex communication to one referenceimpulse radio and said at least one mobile impulse radio is an at leastone impulse radio transmitter transmitting simplex communications toeach reference impulse radio available.
 12. The system for person orobject position location utilizing Impulse Radio of claim 7, whereinsaid plurality of reference impulse radios are impulse radiotransceivers in duplex communication with each other and said at leastone mobile impulse radio is at least one impulse radio receiverreceiving simplex communications from each reference impulse radioavailable.
 13. The system for person or object position locationutilizing Impulse Radio of claim 7, wherein said plurality of referenceimpulse radios are impulse radio transceivers in duplex communicationwith each other and said at least one mobile impulse radio is an atleast one impulse radio transmitter transmitting simplex communicationsto each reference impulse radio available.
 14. The system for person orobject position location utilizing Impulse Radio of claim 7, whereinsaid plurality of reference impulse radios are impulse radiotransceivers in duplex communication with each other and said at leastone mobile impulse radio is an at least one impulse radio transceivertransmitting duplex communications to each reference impulse radioavailable.
 15. The system for person or object position locationutilizing Impulse Radio of claim 7, wherein said plurality of referenceimpulse radios are impulse radio transceivers in duplex communicationwith each other and said at least one mobile impulse radio is an atleast one impulse radio receiver receiving simplex communications fromeach reference impulse radio available.
 16. The system for person orobject position location utilizing Impulse Radio of claim 7, whereinsaid plurality of reference impulse radios are impulse radiotransceivers in duplex communication with each other and said at leastone mobile impulse radio is at least two impulse radio receiversreceiving simplex communications from distinct reference impulse radios.17. The system for person or object position location utilizing ImpulseRadio of claim 7, wherein said plurality of reference impulse radios areimpulse radio transceivers in duplex communication with each other andsaid at least one mobile impulse radio is a combination of mobileimpulse radio transceivers, transmitters or receivers in simplex orduplex communication with any available said reference impulse radios astheir transmission abilities dictate.
 18. The system for person orobject position location utilizing Impulse Radio of claim 7, whereinsaid plurality of reference impulse radios are impulse radiotransceivers in duplex communication with each other and using steerablenull antennae and said at least one mobile impulse radio is an at leastone impulse radio transceiver transmitting duplex communications to eachreference impulse radio available.
 19. The system for person or objectposition location utilizing Impulse Radio of claim 7, wherein saidplurality of reference impulse radios are impulse radio transceivers induplex communication with each other and said at least one mobileimpulse radio is an at least one impulse radio transceiver usingsteerable null antennae to transmit duplex communications to eachreference impulse radio available.
 20. The system for person or objectposition location utilizing Impulse Radio of claim 7, wherein saidplurality of reference impulse radios are impulse radio transceivers induplex communication with each other and using difference antennae andsaid at least one mobile impulse radio is an at least one impulse radiotransceiver transmitting duplex communications to each reference impulseradio available.